81900084 has 96 divisors (see below), whose sum is σ = 234372096. Its totient is φ = 21726720.

The previous prime is 81900061. The next prime is 81900097. The reversal of 81900084 is 48000918.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 118179 + ... + 118869.

It is an arithmetic number, because the mean of its divisors is an integer number (2441376).

Almost surely, 2^81900084 is an apocalyptic number.

81900084 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81900084, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117186048).

81900084 is an abundant number, since it is smaller than the sum of its proper divisors (152472012).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81900084 is a wasteful number, since it uses less digits than its factorization.

81900084 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 805 (or 803 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 30.

The square root of 81900084 is about 9049.8665183526. The cubic root of 81900084 is about 434.2716202679.

The spelling of 81900084 in words is "eighty-one million, nine hundred thousand, eighty-four".